In some applications, web cutters are used to cut continuous paper webs into sheets. Web cutters may be used to provide sheets for use in various paper handling machines, such as mail processing machines, for example.
Mail processing machines are typically used by organizations such as banks, insurance companies, and utility companies for producing a large volume of specific mailings where the contents of each mail item are directed to a particular addressee. A typical mail processing machine has a number of interconnected subsystems. As shown in FIG. 1, an example of a mail processing machine 1 has a paper supply module 10 for supplying a continuous web 5 of printed material, a paper cutter 20 to cut the web into sheets 8, a sheet accumulator 30 to stack the sheets into separate stacks or collations 12, and an inserter 50 for inserting each collation into an envelope 15 supplied by an envelope supply module 40. After the inserting stage, the stuffed envelopes 18 are moved to the next stage 60 where addresses and postage indicia are provided on the envelopes.
Continuous web cutters are known in the art. In some web cutters, the web is provided as a fanfold stack. In a fanfold stack, the web is perforated and folded at the crosswise perforations. The web may have sprocket holes on both sides of the web, so that a tractor with pins can be used to engage the sprocket holes for moving the web toward the cutter. The sprocket holes are typically provided on perforations on each side of the web, and the side perforations are removed from the linked sheets before the linked sheets are moved into a cutter module, where the linked sheets are cut into separate sheets.
In some high speed web handling systems, a vacuum plenum is used to feed the web to the cutter or to hold down the web for cutting. Typically, the cutter uses a guillotine cutting module to cut the web crosswise into separate sheets at the crosswise perforations. In some devices, the guillotine cutting module has two cutting blades that are positioned on opposite sides of a perforation during a cutting cycle. The two cutting blades are simultaneously lowered to shear off the portion of the web immediately adjacent to the perforation. The removed portion is sometimes referred to as a “chip.” The blades are simultaneously withdrawn from the paper path to allow the web to advance.
In other devices, the guillotine cutting module has only one cutting blade to remove the chip by shearing the web twice in each cutting cycle, one in front of the perforation and one behind the perforation.
The chips, along with any other cutting debris, are normally removed from the cutter so that they do not interfere with the cutting operation. Typically, forced air is used to blow the chips away from the cutting area into a vacuum waste system. If the forced air temperature is significantly different from the ambient air temperature around the cutting area, the cutting blades may warp. Warpage in the blade assembly may accelerate blade failure or render the blades inoperable.